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<a name="g_t_002eword-expressions"></a>
<h3 class="section">7.103 <code>.word <var>expressions</var></code></h3>

<a name="index-word-directive"></a>
<p>This directive expects zero or more <var>expressions</var>, of any section,
separated by commas.
</p>
<p>The size of the number emitted, and its byte order,
depend on what target computer the assembly is for.
</p>
<a name="index-difference-tables-altered"></a>
<a name="index-altered-difference-tables"></a>
<blockquote>
<p><em>Warning: Special Treatment to support Compilers</em>
</p></blockquote>

<p>Machines with a 32-bit address space, but that do less than 32-bit
addressing, require the following special treatment.  If the machine of
interest to you does 32-bit addressing (or doesn&rsquo;t require it;
see <a href="Machine-Dependencies.html#Machine-Dependencies">Machine Dependencies</a>), you can ignore this issue.
</p>
<p>In order to assemble compiler output into something that works,
<code>as</code> occasionally does strange things to &lsquo;<samp>.word</samp>&rsquo; directives.
Directives of the form &lsquo;<samp>.word sym1-sym2</samp>&rsquo; are often emitted by
compilers as part of jump tables.  Therefore, when <code>as</code> assembles a
directive of the form &lsquo;<samp>.word sym1-sym2</samp>&rsquo;, and the difference between
<code>sym1</code> and <code>sym2</code> does not fit in 16 bits, <code>as</code>
creates a <em>secondary jump table</em>, immediately before the next label.
This secondary jump table is preceded by a short-jump to the
first byte after the secondary table.  This short-jump prevents the flow
of control from accidentally falling into the new table.  Inside the
table is a long-jump to <code>sym2</code>.  The original &lsquo;<samp>.word</samp>&rsquo;
contains <code>sym1</code> minus the address of the long-jump to
<code>sym2</code>.
</p>
<p>If there were several occurrences of &lsquo;<samp>.word sym1-sym2</samp>&rsquo; before the
secondary jump table, all of them are adjusted.  If there was a
&lsquo;<samp>.word sym3-sym4</samp>&rsquo;, that also did not fit in sixteen bits, a
long-jump to <code>sym4</code> is included in the secondary jump table,
and the <code>.word</code> directives are adjusted to contain <code>sym3</code>
minus the address of the long-jump to <code>sym4</code>; and so on, for as many
entries in the original jump table as necessary.
</p>

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